化简 x2-y2+2y-1就今天

化简 x2-y2+2y-1就今天 x2-y2-2y-1 因式分解 已知x,y满足（x2+y2）(x2+y2-1)=2,则x2+y2的值为多少?x2,y2表示x和y的平方 已知实数x.y满足（x2+y2）（x2+y2-1）=2,求x2+y2的值 (x2-y2)-4(2x2-3y) 已知x2+4y2+x2y2+1=6xy,则(x4-y4)/(2x2+xy-y2)*(2x-y)/(xy-y2)/(x2+y2/y)2= y=x+√(1-x2) y2=x2+(1-x2)+2x√(1-x2) 2/1(x2-y)+3/1(x-y2)+6/1(x2+y2) x-y=1 证明x2+y2+1/x2+1/y2大于等于17/2 x2+y2=1和x2+y2-4x+2y=4解这组方程, 已知实数x,y满足方程x2+y2-4x+1=0求x2+y2+2x的最值x2+y2我会求,加个2x我就不会了 -(x2+y2)+[-3xy-(x2-y2)]化简X=-1,y=2X2表示X的2次方 3XY表示XY乘3 先化简,再求值:2x2-y2+2y2-3x2-2y2+x,其中x=-1,y=2 化简：1/2x-1/(x+y).[x2-y2+(x+y)/2x 思考题：先化简,再求值：(xy-y2)÷x2-2xy+y2/y×x2-y2/y2,其中x=1/2,y=-1 解方程组 ｛3x2-y2=8 {4x2+12xy+9y2=1 {x2+2xy+y2-4=0 x2+xy+y2=4 4x2-9y2=0 x2-2xy+y2-1=0还有{x2+y2=4xy-y2+4=0x2-----x的平方 y2------y的平方 还有{2x-3y=12x2-3xy+y2-4x+3y-3=0 x2-2xy+y2-1/x-y-1 证明：x2+y2+1>2(x-y-1)